The operating temperature within a gas turbine is both thermally and chemically hostile. Advances in high temperature capabilities have been achieved through the development of iron, nickel, and cobalt-based superalloys and the use of environmental coatings capable of protecting superalloys from oxidation, hot corrosion, etc.
In the compressor portion of a gas turbine, atmospheric air is compressed to 10-25 times atmospheric pressure, and adiabatically heated to 700° F.-1250° F. (371° C.-677° C.) in the process. This heated and compressed air is directed into a combustor, where it is mixed with fuel. The fuel is ignited, and the combustion process heats the gases to very high temperatures, in excess of 3000° F. (1650° C.). These hot gases pass through the turbine, where airfoils fixed to rotating turbine disks extract energy to drive an attached generator which produces electrical power. To improve the efficiency of operation of the turbine, combustion temperatures have been raised. Of course, as the combustion temperature is raised, steps must be taken to prevent thermal degradation of the materials forming the flow path for these hot gases of combustion.
Many hot gas path articles are fabricated using welding processes. It is desirable for weld joints in or around such articles to have increased operational properties such as crack resistance. Concentrated and non-distributing thermal and/or residual stress along such welds can result in decreased operational properties.
A process of fusion joining a non-uniform article, such as a turbine blade, to distribute thermal and/or residual stress and a non-uniform article having such features would be desirable in the art.